03. MAGNITUDE AND SCOPE OF DROWNING

Unintentional drowning is a global tragedy that impacts all ages but especially the young. The CDC's National Center for Injury Prevention and Control (NCIPC) in concert with the National Center for Health Statistics (NCHS) created WISQARS (Web-based Injury Statistics Query and Reporting System) to assist the public health community and others in accessing and evaluating injury data. Because of delays in reporting, reviewing and analyzing data from multiple agencies, drowning data and statistics are two years in arrears. Multiple-year data and statistics vary depending upon similar reporting and analytical constraints.

The summary in Table 1 for fatal unintentional drowning for years1999-2009 and non-fatal unintentional drowning for years 2000-2010 (i.e., United States all causes, ages and races, and both sexes) was accessed through WISQARS (9, 10). The rates for unintentional drowning fatalities are about two-thirds of the non-fatalities. Since a significant majority of the reported non-fatalities are for morbidity, which usually indicates being seen in an emergency room or being hospitalized, the actual number of non-fatal drownings is unknown because there is often no reporting of cases without morbidity.

Table 2 estimates the impact of drowning on the years of productive life lost (YPLL) for unintentional drowning fatalities (i.e., United States, all causes and races, all ages before 65, and both sexes) for the years 1999 to 2009 was also accessed through WISQARS (11). The statistic is skewed due to the disproportionate number of drowning fatalities among children aged 1 to 19 whose lives had barely, if ever, reached the beginning of their productive years.

In 2009, drowning was the tenth leading cause of unintentional injury fatalities in the United States, but ranked first for children aged 1 to 4, second for children aged 5 to 9, and fourth for children and early teens aged 10 to 14 (Figure 1.) (12).

Figure 1. U.S. 2009 Ten Leading Causes of Unintentional Injury Deaths by Age Group (12)

To put the previous chart (Figure 1.) in perspective regarding the impact of unintentional injury drowning by age groups, the CDC's WONDER (Wide-ranging Online Data for Epidemiologic Research) provides tables, charts and graphs with compressed mortality data for a variety of disease statistics based on queries utilizing ICD-10 codes, as well as other relevant factors. Figure 2 represents the United States crude rate of unintentional injury drowning fatalities by age group (13). The graphic demonstrates the significance of infant and toddler (i.e., children aged 1 to 4) mortality (2), which is similar to the global burden of drowning in young children, albeit a larger crude rate for children aged 5 to 14 occurs worldwide than in the United States (4).

Figure 2. U.S. Crude Rate of Unintentional Drowning by Age Group 1999-2008 (13)

For drowning data compiled in the years 2000 to 2006, WISQARS was accessed to provide an age-adjusted map of unintentional injury deaths by drowning for the 50 states (i.e., United States, all causes and races, and both sexes) (Figure 3.) (14). The United States annualized age-adjusted rate for unintentional drowning was 1.39 per 100,000 in 2000-2006.

Figure 3. U.S. Age-Adjusted Unintentional Drowning Deaths by State (14)

In reviewing the epidemiology of drowning, Branche, et al, (2005) found that in the United States and other global temperate zones there is a marked seasonality to drowning statistics (15). Generally, the lowest drowning rates were found in the winter months, and the highest rates occurred in the summer months. In the tropics and subtropics, those differences are similar but more muted because of the influx of tourists seeking warmer climes. Also, drowning fatalities were found to increase when alcohol or drugs were involved and when water activities occurred in unfamiliar locations and environments, as well as at night.

The magnitude of the drowning problem is suppressed by many factors other than just terms and definitions. Branche, et al, (2005) implicated poor surveillance systems, bureaucratic delays, procedural flaws and lack of oversight (15). If the person who drowned is not found soon after the event, medically examined or autopsied, or not declared dead by drowning (i.e., listed as the death certificate's primary or secondary cause), that statistic may not be reported. Depending upon emergency room and hospital procedures, a person who drowned but was revived and survives for awhile before dying of complications may not be reported as a drowning fatality. For non-fatal drowning with no morbidity (i.e., neither seen in an emergency room nor hospitalized), there are scant data. The actual population exposed to the risk of drowning is unknown, and so the entire population, known as the standard population, is used as the denominator to estimate a crude rate. Given those and other caveats, the true extent of unintentional drowning, whether fatal or non-fatal, is far greater than what is reported.